children planting potato in raised beds on farm

A Window of Opportunity for Planting Potatoes

If you live in the Tri-County Agriculture Area (TCAA) which includes Putnam, Flagler and St. Johns Counties, you’ve probably noticed that we’ve been a bit wetter than normal for this time of year.  Just to put this extraordinarily wet year in perspective, I have acquired data from the UF Florida Automated Weather Network (FAWN), which can be accessed at https://fawn.ifas.ufl.edu/.  To adequately represent the TCAA, I specifically assessed data from three different FAWN stations located in Hastings (St. Johns County), Putnam Hall (West Putnam County) and Pierson (approximately 5 miles SW of the Flagler County boundary).  Over the last 20 years, the monthly average rainfall at these three stations (combined) has been 2.21” in December and 2.50” in January.  In December 2018, the average rainfall recorded across these three stations was 8.02” (6.60” in Hastings, 10.51” in Putnam Hall, and 6.59” in Pierson).  Likewise, in January 2019, the average rainfall recorded across these three stations was 4.16” (3.49” in Hastings, 5.67” in Putnam Hall, and 3.32” in Pierson).  So if you enjoy numbers, you will appreciate that exercise, but if you don’t care for numbers let’s just say it has been a very wet winter so far!

This rainfall certainly impacts our potato growers across the region.  Farmers usually appreciate the natural irrigation supply from the sky, but excessive rainfall creates many challenges for  planting potatoes.  The fields are wet and large equipment tends to get bogged down in the mud.  Determining specific planting dates is a challenge because too much water can cause the seed potatoes to rot before they have time to sprout.  The pre-plant fertilizer will leach more quickly through the soils, requiring additional fertilizer to be added to promote emergence.  The fumigant used to control soil nematodes may stay or remain trapped in the soils longer due to the higher soil moisture content.  Most farmers understand the devastation that can come from plant-parasitic nematodes, which are microscopic roundworms that attack the root system of plants.  Soil fumigation is one way to control and manage nematodes, while other methods include crop rotation with less susceptible or resistant cover crops such as sunn hemp   http://blogs.ifas.ufl.edu/putnamco/2018/07/31/sunn-hemp-not-industrial-hemp/

One of the services that the UF/IFAS Agriculture Extension Agent for Putnam/Flagler County provides is a field screening of the soils to ensure that fumigant concentrations are safe for planting potatoes.  The device we use to detect fumigant concentrations is a photoionization detector (PID) manufactured by Honeywell Rae Systems known as the MiniRAE 3000.  After proper calibration, the instrument can be taken into the field to screen soils directly for volatile organic compounds that are present within common fumigants.  A slight correction factor must be used to calculate precise concentrations for different fumigants.  For example, a common soil fumigant is Telone II (active ingredient is 1.3-dichloropropene) which is a liquid that quickly converts to a gaseous phase upon application.  It is important to compare that active ingredient with the calibration gas used for the instrument (isobutene) to make sure any necessary correction factor is applied.  In the case of Telone II, it is essentially a 1:1 correlation and so there is no need for a correction factor.  However, if Telone C-35 (which consists of 35% chloropicrin) is the fumigant of choice, a correction factor must be applied if the device is calibrated with isobutene.

Agriculture Agents tests soil for fumigant concentration   Planted potatoes with tractor in background

At the Hastings Agriculture Extension Center, we managed to find a window of opportunity between rain events to plant our potatoes at the 4-H TCAA Potato Field Day on January 21, 2019.  We had 63 attendees (ages 5 to 18) representing five of our surrounding counties and Extension Agents from all of the TCAA UF/IFAS office participated.  There were several educational stations for the kids to attend and my role was to focus on the importance of soil type, structure and pH associated with the potato crop.  Instilling these valuable lessons and providing hands-on opportunities for the youth to personally engage in crop production is essential for our future.

Kids hold potato seeds in a basket for planting  Six year old collects soil from a potato field two teenage children collecting soil from field with soil auger

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